The overall goal is to develop systematic methods of predicting the transport and fate of toxic chemicals in aquifers, emphasizing in particular the effects of physical and chemical heterogeneity of field- scale transport and transformation processes. The applied goal is to provide methods of using data from small-scale controlled laboratory experiments to predict the behavior of contaminants at chemical waste disposal sites involving transport over distances on the order of a kilometer, this being the field scale pertinent to problems of possible human exposure via drinking water supply wells as is found in the area surrounding the Superfund Labs in the Aberjona Basin. The fundamental goal is to understand and quantify the dominant large-scale processes which control transport and transformation of chemicals under field conditions. The approach proposed here will make it possible to predict the degree of contaminant attenuation in terms of the geologic heterogeneity of individual sites and the transformation properties of individual chemicals. By quantifying this important link in the exposure to man in terms of site-specific features, we establish a sound basis for controlling existing hazardous waste sites and regulating future waste disposal activities. The specific approach consists of the following: 1. Development of stochastic theories which describe the large-scale transport and transformation processes and incorporate realistic descriptions of the effects of and interactions between the heterogeneities in the physical and chemical/biological processes of the aquifer. 2. Field testing and demonstration of the application of the resulting theory at an actual contaminated waste disposal site in the Aberjona Basin.